![]() The flowers of many plants rely on visits from bees and other organisms to assist in transferring pollen from stamens to stigmas, which initiates reproduction and bees and other flower visitors need floral resources to survive. Carnivores, like the crab spider, lie in wait to attack. As is this case with other animals who come to feed at the watering hole, a flower-visiting bee makes itself vulnerable to a variety of predators. It comes in search of food in the form of pollen and nectar. When a bee approaches a flower, it is essentially approaching the watering hole. In other words, while we still have a lot to learn, the impact these tiny but skillful hunters have should not be underestimated. There are so many different species of crab spiders, and they are commonly found on flowers around the globe, so “their impact on plant evolution may be widespread among angiosperms.” highlight their importance in such studies. As far as crab spiders go, Knauer, et al. One way to gain a better understanding is to investigate the effects of predators on both pollinators and herbivores in the same study, since many of the papers included in the meta-analysis focused on only one or the other. Additionally, as the authors note, “plants may be buffered against loss of pollination by attracting different types of pollinators, some of which are inaccessible to carnivores.”īut again, there is still so much to discover about these complex interactions. This protects pollinators from predation and helps explain why plant-pollinator interactions are not disrupted as easily by carnivores. Many pollinating insects have an advantage over plant-eating insects because they move quickly from flower to flower and plant to plant, unlike many herbivores which move more slowly. This suggests that carnivores, overall, have a net positive effect on plant fitness. They concluded that where carnivores “disrupted plant-pollinator interactions, plant fitness was reduced by 17%,” but thanks to predation of herbivores, carnivores helped increase plant fitness by 51%. Included were a range of studies involving sit-and-wait predators (like crab spiders and lizards) as well as active hunters (like birds and ants) and the effects of predation on both pollinators and plant-eating insects. A meta-analysis published in the Journal of Animal Ecology in 2011 looked at the research that had been done up to that point. Predator-pollinator-plant interactions are still not well understood, and there is much to learn through future research. ![]() This compound not only attracts pollinators, but is also emitted when plants experience herbivory, possibly to attract predators to come and prey on whatever is eating them.īut none of these studies are one size fits all. also determined that bees and crab spiders are attracted to the same floral scent compound, β-ocimene. Bees are buckler-mustard’s main pollinator, and in concurrence with other studies, they significantly avoided flowers when crab spiders were present. Four populations of buckler-mustard ( Biscutella laevigata ssp. that examined the trade-off that occurs when crab spiders are preying on both pollinators and florivores. In April of this year, Nature Communications published a study by Knauer, et al. In which case, crab spiders can benefit a plant, saving it from reproduction losses by eating insects that eat flowers. Any flower visiting insect may become a crab spider’s prey, and that includes florivores. ![]() ![]() Peruvian lily ( Alstroemeria aurea) via wikimedia commonsīut missing from this discussion is the fact that crab spiders don’t only eat pollinators. The most abundant and effective pollinator, the buff-tailed bumblebee, was deterred by the spiders, leading the researchers to conclude that, “changes in pollinator behavior may translate into changes in plant fitness when ambush predators alter the behavior of the most effective pollinators.” Bumblebees and other bees were the most frequent visitors to the flowers and were also the group “most affected by the presence of artificial spiders, decreasing the number of flowers visited and time spent in the inflorescences.” This avoidance had a notable effect on plant reproduction, namely a 25% reduction in seed set and a 15% reduction in fruit weight. found that pollinating insects avoided the flowers of Peruvian lily ( Alstroemeria aurea) when artificial spiders of various colors and sizes were placed in them. In a study published in Ecological Entomologyearlier this year, Gavini, et al. Now we ask, what effect, if any, does this interaction have on a crab spider infested plant’s ability to reproduce? More importantly, what are the evolutionary implications of this relationship? Thus, pollinating insects tend to avoid flowers that harbor crab spiders. Crab spiders that hunt in flowers prey on pollinating insects. ![]()
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